Improvement in processes of preparing gelatine-plates for printing



UNITED STATES PATENT OFFICE;

' ERNEST EDWARDS, OF BOSTON, MASSACHUSETTS, ASSIGNOR TO JAMES R.

OSGOOD, SAME PLACE.

iMPROVEMENT lN PROCESSES 0F PREPARING GELATlNE-PIATES FOR PRINTING.

Specification forming part of Letters Patent No. 169,166, dated January26, 1875; application filed April 27, 1874.

I To all whom it may concern:

- sorbent by certain well-known means, such asthe formation of chromicacid,by the aotiqn of light upon bichromatized gelatine, or by theapplication of chrome-alum or tannin. In previous applications of thisprinciple, those p0r-' tions of the gelatine which by such means arerendered non-absorbent have been used, by various devices, to producetlne print or picture. I have discovered, however, that those portionsof the gelatine whichafter such treatment remain still absorbent mayalso be used to produce a print or picture, by causing such remainingabsorbent parts to absorb or tak e up a quantity of water containing insolution any convenient color or dye. It will be readily understood.that, by placing paper or other suitable material on such a surface, andapplying sufiicient pressure, the paper or other material will receivethe color from the gelatine-plate in just such proportion as thegelatine has been allowed to remain absorbent.

My invention consists in produeingimpressions with colors known as dyes,as distinguished from printing-inks, from plates consisting of gelatine,gum, albumen, fibrine, or analogous substances which are absorbent ofwater,-the parts which are not required to print having'bee'n renderednon-absorbent of water, or otherwise suitably prevented from printing.

I will describe the mode by which I have successfully prepared andprinted from such plates according to my said'invention.

Upon a suitable surface of metal, wood,

stone, glass, or other suitable material, I place a layer of gelatine,gum, albumen, fibrine, or analogous substance, on-which an image hasbeen or is to be produced, by rendering such portions as are notrequired to print non-absorbent of water by any of the well-known means.In preparing the gelatine or equiva lent plate, I have found thefollowing to be a convenient formula: I take of gelatine, one ounce;water, six ounces; .bichromate, thirty grains. I dissolve the gelatineand bichromate in the water, heated for the purpose, and spread themixture upon a surface of slate. When dry the plate is to be exposed tolight under a photographic] positive, (as distinguished from anegative.) After an exposure suificient to render non-absorbent thoseparts not to be printed, the plate is washed with water till allbichromate has disappeared. It 7 In place is dried, and is then readyfor use. of a photographic pbsitive a design or tracing may be used, orthe bichromate may be omitted and a design drawn directly on thegelatine (or transferred thereto) with chrome-alum. Or a design may bedrawn or transferred to the gelatinein an opaque or water-proof varnish,the portions of the gelatine not covered with the varnish being thenrenderednon-absorbent; or a stencil-plate or mask maybe used, so as to,mechanically prevent the portions of the gelatine covered by it fromimparting any of the solution in those parts to the paper on which theimpression is to be made.

Impressions may be taken from the plate prepared as above described inthe following manner: The surface of the prepared gelatine or equivalentplate is to be wetted or dampened with a solution in water of thedesired color, and the surplus moisture is to be removed. by anyconvenient means. The paper or other material on which the image is tobe printed is then to be pressed upon the surface of the plate, so as toreceive a portion of the color.

As the colors to be used in this kind of printing and 'known as dyes aresoluble in water, and as these colors are to be applied to I the surfaceof the plate in solution, they will not be absorbed by the parts of theplate which have been rendered non-absorbent of water, but in the otherportions they will be absorbed just in proportion as the absorbentproperty has been modified by the treatment which the gelatine hasreceived. \Vhere the colors used are dyes which require mordants tostrengthen the color, the dyes and mordants may beapplied in anyconvenient manner or order. Care must be taken, however, to use onlysuch dyes or mordants as do not injuriously affect the 'gelatin'e,plate. The following are convenient formulas: First. Mordant to beapplied to the paper: Solution of photo-chloride of tin,'one part;water, nine parts. For wetting or dampening the gelatine plate, asaturated solution of extract of logwood.

Second. A saturated solution of aniline-purple, used alone, or withamordant, where necessary, of perchloride of tin.

Third. Chloride of cobalt, one part; water, ten parts.

The image in this case does not appear till heat is applied. On coolingit disappears, and

heat is always necessary to redevelop it.

My said process is also applicable to printing on fabrics, and on allother. material suitable for receiving the action of dyes.

What I claim as my invention, and desire to secure by Letters Patent,is-

The described process of printing from plates of gelatine, gum, albumen,and other analogous bodies which are absorbent of water, with solublecolors known as dyes, in contradistinetion to those known asprinting-inks, the parts not required to produce an impression'havingbeen previously rendered non-absorbent of Water (and hence incapable ofprinting) either by exposure to light, the application of a coagulatingsubstance, an opaque varnish or mat, or other suitable means,substantially as specified, and for the purpose set forth.

ERNEST EDWARDS.

Witnesses:

WALTER RowLANDs, K; L. BERGSTROM.

